In liquid-phase reactions wherein gaseous products are produced, it is often desirable, if not necessary, to separate the gaseous product from any gaseous reactants remaining from, or byproducts produced by, the liquid-phase reaction. The recovery of said unreacted reactants and reaction byproducts from such reactions can pose many manufacturing difficulties, and in the least can be energy intensive. Performing such separations by cooling the reactor effluent and returning the condensed material to the reactor can undesirably reduce the operating temperature within the reactor, which can, in turn, hinder the reaction kinetics. Performing such separations by absorbing the reactor effluent into a cool liquid medium and returning the absorbed material to the reactor can have the same cooling effect, as well as dilution of the reactor contents if a liquid other than the liquid in the reactor is used for absorption. Adding heat to overcome said cooling effect can be costly. Removal of added liquid used for absorption, either from the reactor or from the absorbed reactants and byproducts prior to returning the latter to the reactor, can also be costly.
Much research has thus been devoted to increasing the efficiency, and thus, decreasing the operating cost, of these processes. Many have proposed the implementation of one or more separate steps, such as distillation or absorption, to achieve separation of the gaseous reactor effluent. However, such separation steps may be the most energy and cost-intensive operations in many manufacturing processes. And, each additional step adds capital cost. Some have proposed the use of absorption fluids other than the liquid from the reactor for carrying out separation of the gaseous reactor effluent. However, any additional liquids can accumulate in the process and cause the need for further separation steps to remove reactants and reaction byproducts from the added liquid so that it can be recycled or increased effluent to purge it from the system.
Efficient, more cost effective methods for the production of gaseous products from liquid-phase reactions, specifically the production of alkyl halides by the liquid-phase hydrochlorination of the corresponding alcohol, are thus needed. Desirably, such methods would produce the desired product with savings of equipment cost, time or energy.